Safety lamp



Nov. 6, 1934. H. w. LUECK ET AL SAFETY LAMPv v Filed Dec. l0, 1932 2 Sheets-Sheet Nov. 6, 1934.

Illlll l H. W. LUECK ET AL SAFETY LAMP Filed Dec.

2 Sheets-Sheet 2 Patented Nov. 6, 1934 SATLS PATENW FFQE SAFETY LAMP Application December 10, 1932, Serial No. 646,576

Claims.

Our invention relates generally to safety lamps and resides particularly in improvements on the so-called Wolf safety lamp, whereby the eicacy of the lamp is increased by providing means for giving an audible signal whenever the lamp becomes extinguished.

In the repair and maintenance of electric power mains, gas mains, water mains, etc., it is frequently necessary for the workmen to descend into manholes. In the past, a number of workmen have been asphyxiated, and explosions have occurred, due to the fact that hydrocarbon gases (e. g., methane, ethane, propane, butane and pentane) resulting from leakage from the gas mains, tend to collect in the manholes and conduit tunnels. rThese gases, in many instances are practically odorless and are thus not noticed by the workmen. This danger is particularly prevalent in cities in which natural gas has been substituted for manufactured gas. It is well known that manufactured gas contains tarry and oily products which tend to collect in the mains and effectively form seals at the pipe joints. The natural gas however, does not contain these tarry and oily products to any appreciable extent, and in fact natural gas tends to absorb such products and carry them from the mains. Thus, mains constructed and operated for use with manufactured gas frequently dry out, with the result that leaks in the mains which were formerly sealed by the tarry and oily products permit the escape of the natural gas.

A number of expediente have been proposed to avoid the possibility of explosions and asphyxiation of workmen entering manholes or tunnels due to the presence of this escaped gas. The method at present employed is to have an inspector analyze the air in each manhole before permitting the workmen to enter. This is a costly procedure, since it requires that a gas inspector be present for each repair operation where it is necessary to have Workmen enter the manhole or tunnel and, furthermore, there is no assurance that the atmosphere in the manhole or tunnel will not become seriously contaminated with gas after the inspection has been made. In addition to these considerations, the apparatus necessary for making an analysis of the atmosphere in the tunnel is expensive and requires such a high degrec of skill for its efficient operation that the ordinary skilled electrician cannot be relied upon to conduct the test properly.

The apparatus of our invention may, however, be used by an unskilled workman, since it automatically gives an audible warning of the presence of a harmful percentage of hydrocarbon gases and may be employed continuously for this purpose while the Workman is in the manhole. 1t will also indicate an insufficient oxygen content in the air.

It is, therefore, an object of our invention to provide an improved means for automatically indicating the presence of harmful percentages of explosive or poisonous gases in the atmosphere or an insufficiency in the oxygen content. 5

A further object is to provide a safety device operable automatically to give an audible Signal whenever the percentage of explosive gases in the atmosphere exceeds a predetermined maximum.

A further object is to provide an improved safety lamp having substantially instantaneously operable means for audibly indicating the extinguishment of the flame of the lamp.

A further object is to provide an improved sig- 5 nal means for indicating when the ame of a safety lamp is extinguished, or when it commences burning within the screened top portion of the lamp.

A further object is to provide an improved safety lamp reliably operable under various conditions of use automatically to give an audible warning when the atmosphere contains a dangerous percentage of explosive gases or contains an insuliicient percentage of oxygen. Q

Other objects will appear from the following U description, reference being had to the accompanying drawings, in which Fig. 1 is a view partly in vertical section showing the improved signal means of our invention incorporated in a safety lamp;

Fig. 2 is a transverse sectional View thereof taken on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary elevational view taken on the line 3-3 of Fig. 1;

Fig. i is a fragmentary vertical sectional view taken on the line 4 4 of Fig'fl Fig. 5 is a fragmentary vertical sectional view taken on the line 5 5 of Fig. 2, and

Fig. 6 is a wiring diagram of the alarm circuit.

The so-called Wolf safety lamp, in conjunction with which our invention may be used, comprises generally a base 1G, in which is incorporated a fuel reservoir for the lamp and which also has igniting mechanism associated therewith. The base l0 has a wick tube 12 extending upwardly therefrom so that the llame 14, at the end of the Wick, will be located near the center of the flame chamber formed by a glass tube 16. The tube 16 rests upon a screen ring 18, a suitable gasket 20 being interposed between the tube 16 and ring 18 to form a cushion and air sealing seat for the glass tube. A screen 22 is secured to the ring 18 and covers a plurality of apertures 24 formed in the lower portion of the ring. A shield 26, having suitable air admission apertures 28, is secured about the upper portion of the base 10 and actsv a's a bafe to prevent sudden gusts of wind from flowing directly into the flame chamber and extinguishing the flame.

The upper end of the glass tube 16 is engaged by a collar 30 which is pressed downwardly by a plate 82 through a suitable slightly resilient corrugated washer 33. The plate 32 is held in position by a plurality of tie rods 34 threaded in a locking ring 86, which is threaded upon a flange 38 formed at the upper end of the base casting 10 and is locked in position by means of a set screw 40. The set screw is substantially enclosed in a protruding boss 42 formed integrally with the ring 36and has a polygonal end portion 44 which is adapted to be engaged by a suitable socket key. A pair of nested screens 46, 48 are secured in a flanged ring 50 which is held clamped in position by the plate 32. A screen cover 52, `preferably of corrugatedsheet metal and substantially cylindrical in shape, is held in position by a pair of annular channel shaped members 54, 56, which are clamped together by bolts 58. A top 60 is secured to the lamp by means of the bolts 58, suitable tubular separators 62 being provided to space the top from the upper channel 56. A handle 64 is suitably secured to the top 60. The lamp thus far described is of more or less conventional construction and is not a part of the present invention, except as the parts thereof may be utilized in combination with the novel improvements invented by us.

It will be understood that the Wolf safety lamp above described is at present used to indicate the presence of foreign gases in the atmosphere and to indicate a deciency of oxygen. In using the lamp, it is ignited by the mechanicall igniter provided and placed in the atmosphere to be tested. The flame, in a normal atmosphere, will burn in the shape substantially as indicated in dotted lines in Fig. 1. When, however, a deficiency of oxygen is present, the name will correspondingly decrease in size and if the deficiency is suiiieiently great will become extinguished. If the atmosphere contains inflammable gases, but does not have a particular deciency in oxygen, the flame will frequently leave the wick and combustion will continue within the chamber formed by the screens 46, 48, the latter preventing propagation of the flame outside of the lamp. The indicator of our invention. is adapted to render an audible signal whenever' the arne is extinguished, cr becomes small due to the deficiency of oxygen, and whenever the llame leaves the wick and combustion continues within the screen chamber.

The audible signal is controlled by a bimetallic thermostatic element 66 formed in a spiral. The inner end of the element 66 is secured to a bracket 68 which is clamped to a bolt 70,

'which is in electrical contact with and supported by a bracket 72, the latter being soldered or otherwise suitably secured to the screen ring 18. A metallic sleeve 74 surrounds the bolt 70, being insulated therefrom by a tube 76 of insulating Y material and by insulating discs 78 and 80.

A collar 82 is mounted for free rotation upon the sleeve 74, the amount of friction between the collar and the sleeve being determined by a spring finger 84, soldered or otherwise secured to the collar 82 and frictionally engaging the sleeve 74. The collar 82 and the sleeve 74 bear against the horizontal portion 86 of a contact plug 88.

A sernicircular shaped wire 90 is soldered to the collar 82 and at its extremity has a wire 92 soldered thereto (Fig. 3) The Wire 92 has an upwardly and horizontally extending arm 94 which, at its end, has axed thereto a contact point 96 of tungsten, platinum, or other suitable material. This point is adapted to Contact with a similar Contact point 98 secured to the extremity of the thermostatic element 66. The wire 92 has a vertically extendingl post portion 100 forming a support for a roller 102 which may be made of any suitable insulating and heat resistant material such, for example, as porcelain.

The contact plug 88, it will be apparent, is in electrical connection with the contact point 96, whereas the contact point 98 isin electrical communication with the metallic ring`18, which may be considered as the ground. When the lamp is properly assembled, the contact plug 88 will engage in a socket formed by a pair of spring fingers 104 which are held in position by a bolt 106, a suitable cup 108 and a tube 110 being utilized to insulate the bolt from the base 10. A recess is formed in the base 10, the walls of the recess being suitably insulated, as shown in Fig. 1, so as to prevent accidental contact with a wire 114 which is electrically connected to the bolt 106. An insulation covered nut 116 is utilized to hold the bolt 106 in place and to maintain the contact with the wire 114.

The wire 114 passes through an opening 118 in a flange 120 formed integrally with the base l0 and is soldered, or otherwise suitably secured, to an upwardly extending contact prong 122 mounted upon an insulating block 124 which is suitably secured to the base 10. A spring finger connection socket 126 is carried in an insulating block 128 mounted upon a casing 130 and is adapted to make electrical contact with the prong 122 when the casing is slid downwardly into its proper position, as shown in Fig. 1. The casing 130 forms a compartment for a battery and buzzer and is Vdetachably secured to the base 10, suitable inwardly extending flanges 132 formed on the casing being engageable behind lugs 134 formed on the base 10.

The casing is preferably a die casting and has an inwardlyextending boss 136 (Fig. 5) which is provided with a threaded counterbore 140. A screw 142 is threaded in the bore 138 of the boss 136 and has a projecting shoulder 144 to limit its movement. A ring 146 is threaded in the bore 140 and serves to limit outward movementA of the screw 142. The screw 1.42 has a polygonal head 148, which may be engaged by a suitable socket keyV to turn the screw into a threaded hole 150 secured to one of the terminals 156 of a battery 158. The other terminal 160 of the battery is connected by a wire 162 with the terminal 164 of a bell or buzzer 166. The other terminal o1' the buzzer is grounded by the connection of the buzzer to the casing 130. The buzzer may be ofA any suitable well known construction capable of giving a relatively loud, audible signal. The

buzzer is mounted directly against the outer wall of the casing 130 so that the latter aids in propagating the sound produced by the former.

In the normal use of the lamp of our invention, the foreman, or other responsible person, in charge of the workmen will light the lamp and thereafter attach the casing 130 with the parts contained therein to the base of the lamp by sliding it downwardly so that the flanges 132 lie beneath the lugs 134, and then lock the casing in position on the base by turning the screw 142 into the hole 150. When the casing is thus attached to the lamp, the necessary electrical con tacts are simultaneously made, the screw 142 assuring a good electrical connection between the casing and the base 10 and the spring socket 126 and prong 122 connecting the live wire of the circuit.

If desired, the apparatus may be tested by attaching the housing 130 to the base 10 prior to lighting the lamp. When thus connected, the buzzer 166 should immediately sound, since the thermostatic element 66 will normally be contracted and the contact points 96 and 98 will be in contact. Then, upon lighting the lamp, the thermostatic element 66 will expand and draw the contact 98 away from the contact 96 and break the electrical circuit to the buzzer. As the element 66 expands, its extremity will engage the roller 102 and swing the arm 99 along with it. The contact points 96, 98 will thus at all times be closely adjacent one another and in position to be closed upon a very slight contraction of the element 66. The lamp is then in condition for use.

When the lamp is placed in an atmosphere which is deficient in oxygen or which contains an excessive percentage of explosive gases, the flame 14 will either be extinguished or it will leave the wick and combustion willv continue within the chamber formed by the screens 46, 48, Under either condition, the thermostatic element 66 will be cooled and contracted, bringing the contact points 96, 98, into contact and closing the circuit to the buzzer. The alarm thus given will apprize the workman that the atmosphere in which he is carrying the lamp is dangerous and warn him to leave.

It will be noted that as the thermostatic element 66 expands, its extremity being in engagement with the roller 102 will withdraw with it the wire arm 90, the movement of the latter being retarded slightly by the spring finger 84. Upon contraction of the thermostatic element 66, due to the extinguishment of the flame, the spring finger 84 will hold the contact 96 stationary and thus the circuit to the buzzer will be closed almost immediately after the ame is extinguished. By thus having the contact 96 moved along with the contact 98, the contacts are always in close proximity to one another, and only a slight cooling of the thermostatic element is necessary to cause the contacts to close the circuit.

The device is thus very sensitive and will give the alarm signal within a few seconds after it is placed in an explosive atmosphere or an atmosphere deficient in oxygen. In the latter case, the flampe may not be immediately extinguished, but may gradually decrease in size. Even a slight decrease in the size or intensity of the flame will cause the thermostatic element 66 to contract sufficiently to close the buzzer circuit. The buzzer will sou'nd continuously until either the flame is rekindled or the casing 130 is removed from the lamp. The foreman or other person in charge of a group of workmen will be the only one provided with a suitable socket key by which the casing 130 may be removed.

The signal apparatus of oui` invention is mounted in the lamp in such manner that it does not interfere in any way with the disassembly of the lamp for inspection and cleaning and does not in any way interfere with the normal operation of the lamp. The thermostatic element 66 is located so that it is not subjected to the high temperatures of the flame and will thus not corrode or deteriorate for a long time. It is so located that it is heated substantially solely by heat radiated from the aine rather than by convection air currents. This is indicated in Fig. 1 by the arrows showing the path of the flow of air through the lamp, wherein it will be seen that the air which comes in contact with the thermostatic element is not directly heated by the flame and that the highly heated gases pass through the center of the thermostatic element.

While we have shown and described a particular embodiment of our invention, it will be apparent to those skilled in the art that various modifications in design and construction may be made without departing from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. In a safety lamp, the combination of flame producing means, a thermostat located above and spaced from the flame produced by said flame producing means, said thermostat comprising a bimetallic thermostatic element having a contact point at its free end, a second contact point movable relative to said first Contact point, friction means for retarding movement of said second contact point, and interconnecting means to cause said second contact point to move with said rst contact point as the latter moves in a direction away from the second contact point; an audible electrical signal, a source of electrical energy, and a circuit connecting said signal, said contact points land said source in series.

2. In a safety lamp for detecting variations in the oxygen content of the atmosphere, the combination of a iiame producing means, an audible signal circuit, and a thermostatic device located adjacent the flame produced by said means and having means for closing said signal circuit upon a predetermined slight reduction in the amount of heat produced by said flame, irrespective of the amount of heat previously produced by the flame.

3. In a safety lamp for the detection of harmful percentages of explosive gases in the atmosphere, the combination of a flame producing means, close meshed screening protecting said flame from the atmosphere, an electric signal circuit, and a thermostat included in said circuit and located adjacent the flame produced by said means, said thermostat comprising a pair of contacts and means to move one of said contacts with the other in one direction upon an increase in temperature whereby said contacts will at all times be in close proximity to one another in position to be closed upon a slight decrease in temperature.

4. In a miners safety lamp of the Wolf type having a removable lower screen supporting ring, a post secured to said ring, a thermostatic electrical Contact element supported by said post, means for insulating one of the contacts of said elements from said post, an electrical connection socket formed in the base of the lamp, and a prong carried by the part insulated from said post and engageable with said socket to form an electrical connection when said ring is placed in position'on the base of the lamp. y

5. In a safety lamp of the Wolf type having a base, a removable inlet screen supporting ring, a chimney screen, and a chimney screen protector, the combination of a casing, means for securing said casing to said protector, an electrically operable audible signal device and an electrical battery mounted within said casing, a thermostatic el-ement, means for mounting said element upon the inlet screen supporting ring, said thermostatic element having a pair of electrical contact members, means for normally insulating said contact members from one another, one of said contact members being electrically connected to said ring, a plug and socket connector having one part connected to one of said contact members and the other part mounted in said base, and electrical conductors to connect said thermostatic contact members, said battery and saidsignal device in series.,

6. In a safety apparatus for the indication of the presence of a harmful percentage of hydrocarbon gases in the atmosphere, the combination of a llame producing means, a thermostatic de- Vvice placed sufciently close to the flame produced by said means to be quickly aiected by the heat radiated therefrom, but spaced sufliciently from the flame and the heated convection currents produced thereby so as not to be appreciably affectedv by heat conducted to it'by the flame, said device comprising a thermostatic element, a pair of movable contacts, one of the contacts being secured to said element, and means operable only While said element is being heated to move the other of said contacts with said iirst named contact at a spaced distance` therefrom; and electrical signal means controlled by the closing of the contacts of said device and operative to provide an attention arresting alarm when the ame of said flame producing means is appreciably reduced in size. Y y

7. In combination, a safety lamp, a thermostat mounted in the flame chamber thereof, a casing,

a battery and an electrically operated audible signal mounted in said casing, cooperating means on said casing and the base of said lamp for detachably securing the casing to the base, and interengaging means on the casing and base for electrically connecting said battery and signal in series with said thermostat upon attaching said casing to the base of the'lamp.

8. In a safety lamp of the Wolf type having a base, a Wick supported in the base, and screened apertures provided for a circulation of air to and from a ilame on said Wick; a coiled bi-metal thermostatic element positioned above the tip of a normal flame on said Wick and spaced laterally therefrom whereby the flame and gases highly heated ,thereby Willnot come into direct contact with the thermostatic element, and an audible signal electric circuit connected in series with said thermostatic element and arranged to be closed by said element When said iiame is eX- tinguished or appreciably reduced in size thereby to indicate a dangerous atmospheric condition.

9. A safety lamp, comprising a flame producing means, a thermostatic element formed in spiral shape around the axis of the name produced by said means, a contact carried by said element, a second contact mounted for movement With said first contact, means on said element' engageable with said second contact to move the latter With said first contact upon expanding movement of said element, and an electrical signal circuit arranged to be closed by said contacts upon contracting movement of said element.

v l0. In combination, a safety lamp, comprising a base, a ame chamber, and a removable inlet screen ring; a thermostat mounted upon said ring and located Within said flame chamber, and interengaging electrical connection means supported by said ring and said base, whereby electrical connectionsto said thermostat Will be completed as an incident to placing said ring in position in said lamp.

HENRY W. LUECK. CHARLES H. DAVIS. URIAH DAVIS. 

